In the course of the century all the remaining independent lands surrounding the Mediterranean were steadily brought under Roman control, being ruled either directly under governors or through puppet kings appointed by Rome. The Roman state itself was plunged into civil war several times, finally resulting in the marginalization of its 500-year-old republic, and the embodiment of total state power in a single man—the emperor.

The internal turbulence that plagued Rome at this time can be seen as the last death throes of the Roman Republic, as it finally gave way to the autocratic ambitions of powerful men like Sulla, Julius Caesar, Mark Antony and Octavian. Octavian's ascension to total power as the emperor Augustus is considered to mark the point in history where the Roman Republic ends and the Roman Empire begins. Some scholars refer to this event as the Roman Revolution. It is believed that the birth of Jesus, the central figure of Christianity took place at the close of this century.

In the eastern mainland, the Han Dynasty began to decline and the court of China was in chaos in the latter half of this century. Trapped in a difficult situation, the Xiongnu had to begin emigration to the west or attach themselves to the Han.

27 BC: The Roman Senate votes Octavian the title of Augustus. Augustus eventually assumes all authority formerly held by the Roman senate becoming the first emperor. This is traditionally taken as the end of the Roman Republic and the beginning of the Principate (27 BC-AD 285).